Magnetic recording mediums having a ferro magnetic metal thin film as a magnetic recording film exhibit good magnetic characteristics suitable for high density recording, but are disadvantageous in that the magnetic recording film is made of a metal thin film that is subject to corrosion and therefore liable to produce errors. Typically, the hardness of the film is so low that its durable resistance to sliding is inferior to that of filler-containing coating-type magnetic recording mediums.
Accordingly, it is common to use Co or alloys of Co--Ni to which approximately 10 weight % of Cr is added. Alternatively, as set forth in "The Symposium on Memory and Advanced Recording Technologies (S.M.A.R.T.)" WS3-B-2, pp. 1-25, San Jose, Calif., May (1986), a carbon protective film is provided on the magnetic recording film on which there is further formed a lubricating layer made of a polar or non-polar lubricant such as fluoroalkyl polyethers. As a result, the medium exhibits some resistance to wear caused by the sliding of a magnetic head on the surface of the medium.
As another example of manufacturing a magnetic recording medium having a protective film, Japanese Laid-Open Patent Application No. 61-96512 discloses a method for providing a protective film of carbon formed on a magnetic recording film. A lubricant is impregnated in the pores of the protective film.